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Question

使用此代碼，我得到一個堆棧溢出錯誤，如果我使用head=0它要求新的操作符。

void *__CRTDECL operator new(size_t size) _THROW1(_STD bad_alloc) 
    {  // try to allocate size bytes 
    void *p; 
    while ((p = malloc(size)) == 0) 
      if (_callnewh(size) == 0) 
      {  // report no memory 
      static const std::bad_alloc nomem; 
      _RAISE(nomem); 
      } 
    return (p); 
    } 



    #include "StdAfx.h" 
    #include "event.h" 


    EventList::EventList() 
     { 
     size = 0; 
     EventList *head = new EventList(); 
     tail = NULL; 


    } 


    EventList::~EventList() 
    { 
    //Do nothing 
    } 

    unsigned int EventList::Size() 
     { 
     return size; 
     } 

    void EventList :: add(Event* ev) 
    /*the event will be added to the correct location based on its time 
     So, always the event at the top (or at location 0) is the most 
     imminent event that must be handled firstly*/ 

     if(size == 0) 
      { 
      head = tail = ev; 
      ev->next = ev->previous = 0; 
      } 
     else 
      { 
      if(ev->eventTime < head->eventTime) 
      { 
      /////////////// 
      ev -> next = head; 
      head -> previous = ev; 
      ev -> previous = 0 ; 
      head = ev; 
      /////////////// 
      } 
     else 
      { 
      //////////// 
      Event* tracer = head; 
      while (tracer -> next != 0) 
       { 
       if (ev -> eventTime >= tracer -> eventTime) 
        { 
        tracer = tracer -> next; 
        } 
       else 
        { 
        ev -> next = tracer; 
        ev -> previous = tracer -> previous; 
        tracer -> previous -> next = ev; 
        tracer -> previous = ev ;       
        } 
       } 
       ////////////// 
       if (tracer -> next == 0) 
        { 
        ev -> next = 0 ; 
        ev -> previous = tracer ; 
        tracer -> next = ev; 
        tail = ev; 
        } 
       //////////// 
      } 
     } 
     size++; 
    } 
    //Remove the most imminent event from the event list to be handled 
    //by the simulator 
    //Since we have an ordered linked list this event is found at the head 
    //of the event list 
    //The retreived event will be found in ev 
    bool EventList :: remove(Event* ev) 
    { 
    /*public ev =new EventList();*/ 
    if(size == 0) 
     { 
     ev = 0; 
     return false; 
     } 
    else 
     { 
     ev =head;  
     //head=ev; 
     if (size != 1) 
      { 
      //head -> next -> previous = 0; 
      head = head -> next ; 
      ev -> next = ev -> previous = 0; 
      } 
     else 
      { 
      head = tail = 0; 
      } 
     return true; 
     } 
    delete head; 
    head=NULL; 
    } 

Answer 1

EventList::EventList() 
{ 
    // ... 
    EventList *head = new EventList(); 
    // ... 
} 

當EventList構造，它開始構建另一EventList。由於您不會終止遞歸，因此最終會耗盡堆棧空間。

（即使你終止了遞歸，你會泄露所有youv'e創建這些EventList的對象，因爲你不指針把它們存放到構造之外。）